The present invention relates generally to an apparatus for planarizing a substrate surface and, more particularly, to a platen assembly containing a polishing pad. The present invention is applicable to manufacturing high speed integrated circuits with high production throughput.
Chemical-mechanical polishing (CMP) is a conventional method of planarizing a substrate. CMP is sensibly employed during the manufacture of semiconductor devices to obtain a uniform surface, and enjoys particular applicability in manufacturing semiconductor devices having submicron feature sizes, such that surface irregularities do not exceed the depth of focus limitations of conventional photolithographic devices.
In conventional CMP techniques, a wafer carrier assembly is rotated in contact with a polishing pad in a CMP apparatus. The polishing pad is mounted on a platen which can be rotated or linearly driven by an external driving force. The wafers are typically mounted on a carrier or polishing head which provides a controllable force, i.e., pressure urging the wafers against the moving polishing pad. The CMP apparatus effects polishing or rubbing movement between the surface of each thin semiconductor wafer and the polishing pad while dispensing a polishing slurry or chemical agent. Conventional polishing pads employed in abrasive slurry processing typically comprise a grooved porous polymeric surface, such as polyurethane, and the abrasive slurry varied in accordance with a particular material undergoing CMP. Fixed abrasive polishing pads comprise a polymeric backing sheet with a plurality of geometric abrasive composite elements adhered thereto. The abrasive elements typically comprise a plurality of abrasive particles in a binder, e.g., a polymeric binder. During CMP employing fixed abrasive articles, a chemical agent is dispersed to provide chemical activity, while mechanical activity is provided by the fixed abrasive elements.
Polishing pads, whether fixed abrasive or conventional grooved polishing pads employed in slurry abrasive processing, typically comprise a polymeric material and are adhered to a metallic platen, e.g., aluminum or stainless steel, by friction or by an adhesive, such as a pressure sensitive adhesive. Periodically, the polishing pads must be replaced. However, it is extremely difficult to remove a polishing pad from the underlying platen. Typically, a large amount of force is required to manually remove the polishing pad from the platen. The time and effort required to remove a polishing pad from a platen adversely impacts manufacturing throughput and, hence, constitutes a distinct disadvantage in the competitive semiconductor manufacturing marketplace.
Accordingly, there exists a need for a method of removing a polishing pad from a platen in an expeditious, efficient and cost effective manner.
An aspect of the present invention is a CMP apparatus comprising a platen and a polishing pad which is easily removable from the platen in a cost effective and efficient manner.
Another aspect of the present invention is a method of removing a polishing pad from a platen in a cost effective efficient manner.
Additional aspects and other features of the present invention will be set forth in the description which follows and in part will become apparent to those having ordinary skill in the art upon examination of the following will maybe learn from the practice of the present invention. The aspects of the present invention may be realized and obtained as particularly pointed out in the appended claims.
According to the present invention, the foregoing and other aspects are implemented in part by an apparatus for polishing a wafer, the apparatus comprising: a platen; a heat softenable adhesive on the platen, means for heating the heat softenable adhesive; and a polishing pad on the heat softenable adhesive.
Another aspect of the present invention is a method of planarizing a wafer, the method comprising: providing a polishing apparatus containing a platen and heating means; adhering a polishing pad to the platen with a heat softenable adhesive; and polishing of the wafer. Subsequently, the heat softenable adhesive is heated with a heating means to a temperature sufficient to soften the heat softenable adhesive and the polishing pad easily removed from the platen.
A further aspect of the present invention is a method of removing a polymeric polishing pad from a metal platen of a polishing apparatus, wherein the pad is adhered to the platen by a heat softenable adhesive, the method comprising heating the heat softenable adhesive to a temperature sufficient to soften the heat softenable adhesive and facilitate removal of the pad.
Embodiments of the present invention comprise forming the platen with internal heating means, such as a heating filament or channels through which a heated fluid is passed. Embodiments of the present invention further comprise employing a heat softenable adhesive which preferentially adheres to the polymeric polishing pad upon being softened by heating and removed from the metallic platen.
Additional aspects of the present invention will become readily apparent to those skilled in this art from the following detailed description, wherein embodiments of the present invention are described, simply by way of illustration of the best mode contemplated for carrying out the present invention. As will be realized, the present invention is capable of other and different embodiments, and its several details are capable of modifications in various obvious respects, all without the parting from the present invention. Accordingly, the drawings and description are to be regarded as illustrative in nature and not as restrictive.